Meet the NAASC


Jonathan Keohane is on sabbatical from teaching at Hampden-Sydney College, a private liberal arts college for young men. After receiving his B.S. in physics from Yale University, Jonathan completed a teacher education program at the University of Oregon and taught high school physics for two years before entering graduate school in astrophysics at the University of Minnesota. While completing his thesis work comparing X-ray and radio emission from supernova remnants, Jonathan spent three years in the Laboratory for High Energy Astrophysics at Goddard Space Flight Center in Greenbelt Maryland. Jonathan then taught for the next five years at the North Carolina School of Science and Mathematics, where he involved his students in research using the Chandra X-ray Observatory. This was followed by a year long post-doc at the Spitzer Science Center, after which Jonathan joined the faculty at Hampden-Sydney College -- where he has been teaching for the past seven years. Jonathan is spending his year at NRAO developing curricula to support the teaching and learning of radio astronomy at the undergraduate and graduate levels.

ALMA Progress

During September, the complement of antennas at the 16500ft elevation Array Operations Site (AOS) reached 20. Sixteen 12m antennas were moved into position on the antenna foundations selected for the beginning of Early Science at the end of the month. In order to use the newly completed pads, complex power shutdowns were completed. Power must be restored quickly after these events so that the sensitive receiver elements do not warm up. The power events were completed successfully. One third of the contracted ALMA antenna total of 66 have now been accepted, outfitted and integrated into the array. A few of those antennas have been transported back to the Operations Support Facility (OSF) for upgrades to components, after which they return to the AOS for use in Early Science and/or Commissioning activities.

A major technical problem of the ALMA Local Oscillator (LO) system is to maintain accurate phase stability in the signals used in the receiver components. The central reference part of the LO system is located at the AOS in the Technical building. From here the signal is used to lock electronic oscillators and derived frequencies in antennas located at distances of many miles across the site via optical fiber. The outgoing frequency is transmitted as the difference between two laser frequencies in the infrared. The required phase stability of the LO signal is equivalent to less than 12 femtoseconds of time, less than 38 femtoseconds of phase noise. This time equivalent phase stability is to a second as a second is to 2.6 million years! The main LO system is named the Central Local Oscillator Article (CLOA). Installation and testing of the final stage of CLOA took place in August; it was accepted in September. The CLOA is now capable of supporting the 66 antennas and four subarrays built for the ALMA consruction project; it may be expanded to provide signals for up to six subarrays and eighty antennas.

During September, the complement of antennas was split for the first time into two subarrays, with signals from one subarray going to the main correlator (now with its second quadrant able to combine signals from 32 antennas) and signals from another going to the Atacama Compact Array (ACA) correlator delivered from Japan. The test was successful. During full operations, ALMA’s powerful correlators can process signals from up to four independently-tuned subarrays.

Principal Investigators of 112 successful proposals of the 919 submitted for Early Science Cycle 0 time were informed of the news. Scientists at the JAO and ARCs worked to translate those proposals selected for the initial complement of compact configuration observations into ‘Schedule Blocks’. These are sequences of commands to the instrument to guide it through the calibrations and source observations needed for successful completion of the projects. Scientists at the ALMA Resource Centers in Europe, North America and East Asia worked with the Principal Investigators to ensure successful project execution. End-to-end operations testing of selected high priority projects have been successfully completed on the array; the tests were successful though efficiency improvements were identified.

This Month at the NAASC

Starting Early Science

Crystal? Al - Observations begin

~ Registration open for December 6, 7 (Kartik)

ALMA Software Development Workshop

ALMA Software Development Workshop

NRAO will host a workshop 12-14 October 2011 in Charlottesville, Virginia to discuss software development plans for ALMA and closely related telescopes. The aim of the workshop is to generate a set of ideas for software applications that will enhance the science output from ALMA, and to stimulate the formation of consortia willing to submit these ideas to the ALMA Development Program for funding (including seed funding via NRAO and full funding via the ALMA Board) and/or the NSF directly. The workshop will concentrate on science data analysis of the large datasets that ALMA will produce. Topics will include line forest analysis, feature finding in large datacubes, matching data to simulations, visualization and compressive sensing.

Outflows, Winds and Jets: from Young Stars to Supermassive Black Holes



The NRAO North American ALMA Science Center (NAASC) will host its 6th annual science workshop – Outflows, Winds and Jets: From Young Stars to Supermassive Black Holes ­– in Charlottesville, Virginia, 3-6 March 2012. The venue is the Omni hotel, located conveniently near downtown Charlottesville. Pre-registration is open at the conference web site. Pre-registration is not required, but will ensure that you receive timely information about the conference program and logistics. Registration will open 1 November 2011.

-- LyndeleVonSchill - 2011-09-15
Topic attachments
I Attachment Action Size Date Who Comment
jets.jpgjpg jets.jpg manage 69 K 2011-09-15 - 16:11 LyndeleVonSchill  
keohane.JPGJPG keohane.JPG manage 742 K 2011-09-20 - 09:50 LyndeleVonSchill  
Topic revision: r6 - 2011-10-03, AlWootten
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